It's already known that a person's social environment can affect
their health, with those who are socially isolated-that is,
lonely suffering from higher mortality than people who are not.
Now, in the first study of its kind, published in the current
issue of the journal Genome Biology, UCLA researchers have identified
a distinct pattern of gene expression in immune cells from people
who experience chronically high levels of loneliness. The findings
suggest that feelings of social isolation are linked to alterations
in the activity of genes that drive inflammation, the first
response of the immune system. The study provides a molecular
framework for understanding why social factors are linked to
an increased risk of heart disease, viral infections and cancer.
Having previously established that lonely people suffer from
higher mortality than people who are not, researchers are now
trying to determine whether that risk is a result of reduced
social resources, such as physical or economic assistance, or
from the biological impact of social isolation on the function
of the human body. "What this study shows is that the biological
impact of social isolation reaches down into some of our most
basic internal processes the activity of our genes." said Steve
Cole, an associate professor of medicine in the division of
Hematology-Oncology at the David Geffen School of Medicine,
and a member of the UCLA Cousins Center for Psychoneuroimmunology.
"We found that changes in immune cell gene expression were
specifically linked to the subjective experience of social distance,"
said Cole, who is also a member of the Jonsson Comprehensive
Cancer Center. "The differences we observed were independent
of other known risk factors, such as health status, age, weight,
and medication use. The changes were even independent of the
objective size of a person's social network."
Cole and colleagues at UCLA and the University of Chicago used
DNA microarrays to survey the activity of all known human genes
in white blood cells from 14 individuals in the Chicago Health,
Aging, and Social Relations Study. Six participants scored in
the top 15 percent of the UCLA Loneliness Scale, a widely used
measure of loneliness that was developed in the 1970s; the others
scored in the bottom 15 percent. The researchers found 209 gene
transcripts (the first step in the making of a protein) were
differentially expressed between the two groups, with 78 being
overexpressed and 131 underexpressed. "Leukocyte (white blood
cell) gene expression appears to be remodelled in chronically
lonely individuals," said. Cole.
Genes overexpressed in lonely individuals included many involved
in immune system activation and inflammation. But interestingly,
several other key gene sets were underexpressed, including those
involved in antiviral responses and antibody production. "These
findings provide molecular targets for our efforts to block
the adverse health effects of social isolation," said Cole.
"We found that what counts at the level of gene expression
is not how many people you know, it's how many you feel really
close to over time." In the future, he said, the transcriptional
fingerprint they've identified might become useful as a 'biomarker'
to monitor interventions designed to reduce the impact of loneliness